Treatment with dimethyl fumarate reduces the formation and rupture of intracranial aneurysms: Role of Nrf2 activation

Dimethyl fumarate treatment for unruptured intracranial aneurysms: a study protocol for a double-blind randomised controlled trial

INTRODUCTION

Intracranial aneurysm (IA) is a common cerebrovascular disease. Considering the risks and benefits of surgery, a significant proportion of patients with unruptured IA (UIA) choose conservative observation. Previous studies suggest that inflammation of aneurysm wall is a high-risk factor of rupture. Dimethyl fumarate (DMF) acts as an anti-inflammatory agent by activating nuclear factor erythroid 2-related factor 2 (Nrf2) and other pathways. Animal experiments found DMF reduces the formation and rupture of IAs. In this study, DMF will be evaluated for its ability to reduce inflammation of the aneurysm wall in high-resolution vessel wall imaging.

METHODS AND ANALYSIS

This is a multi-centre, randomised, controlled, double-blind clinical trial. Three hospitals will enrol a total of 60 patients who have UIA with enhanced wall. Participants will be assigned randomly in a 1:1 proportion, taking either 240 mg DMF or placebo orally every day for 6 months. As the main result, aneurysm wall enhancement will be measured by the signal intensity after 6 months of DMF treatment. Secondary endpoints include morphological changes of aneurysms and factors associated with inflammation. This study will provide prospective data on the reduction of UIA wall inflammation by DMF.

ETHICS AND DISSEMINATION

This study has been approved by Medical Ethics Committee of the Beijing Tiantan Hospital, Capital Medical University (approval no: KY2022-064-02). We plan to disseminate our research findings through peer-reviewed journal publication and relevant academic conferences.

TRIAL REGISTRATION NUMBER

NCT05959759.

Unleashing the Potential of Nrf2: A Novel Therapeutic Target for Pulmonary Vascular Remodeling

Pulmonary vascular remodeling, characterized by the thickening of all three layers of the blood vessel wall, plays a central role in the pathogenesis of pulmonary hypertension (PH). Despite the approval of several drugs for PH treatment, their long-term therapeutic effect remains unsatisfactory, as they mainly focus on vasodilation rather than addressing vascular remodeling. Therefore, there is an urgent need for novel therapeutic targets in the treatment of PH. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a vital transcription factor that regulates endogenous antioxidant defense and emerges as a novel regulator of pulmonary vascular remodeling. Growing evidence has suggested an involvement of Nrf2 and its downstream transcriptional target in the process of pulmonary vascular remodeling. Pharmacologically targeting Nrf2 has demonstrated beneficial effects in various diseases, and several Nrf2 inducers are currently undergoing clinical trials. However, the exact potential and mechanism of Nrf2 as a therapeutic target in PH remain unknown. Thus, this review article aims to comprehensively explore the role and mechanism of Nrf2 in pulmonary vascular remodeling associated with PH. Additionally, we provide a summary of Nrf2 inducers that have shown therapeutic potential in addressing the underlying vascular remodeling processes in PH. Although Nrf2-related therapies hold great promise, further research is necessary before their clinical implementation can be fully realized.

Chronic alcohol feeding alters lymph and plasma proteome in a rodent model

Chronic alcohol consumption in rodents induces mesenteric collecting lymphatic vessel hyperpermeability, lymph leakage, and consequent immunometabolic dysregulation of the perilymphatic adipose tissue (PLAT). The specific lymphatic components mediating PLAT immunometabolic dysregulation remain to be identified. Specifically, whether alcohol impacts lymph composition is unknown. This study aimed to determine alcohol associated changes in lymph and plasma proteome. Adult male rats were fed a Lieber-DeCarli liquid diet containing 36 % of calories from alcohol for 10 weeks. Time-matched control animals were pair-fed. At sacrifice lymph was collected for 2 h using the lymph-fistula technique and plasma was collected prior to sacrifice. Quantitative discovery-based proteomics identified a total of 703 proteins. An integrative approach combining Ingenuity Pathway Analysis (IPA) and an unbiased network analysis using WGCNA (Weighted Gene Co-expression Network Analysis) was used to analyze the proteomics data. IPA results identified significant upregulation of a cluster of apolipoproteins in lymph from alcohol-fed animals compared with pair-fed controls and a downregulation of 34 proteins in the plasma from alcohol-fed animals. WGCNA analysis identified several candidate hub proteins in the lymph that were also significantly differentially expressed in lymph from alcohol-fed animals compared to that of pair-fed controls. WGCNA analysis of plasma identified a module without significant enrichment of differentially expressed proteins. Of the 59 proteins contained within this module, only 2 were significantly differentially expressed in plasma from alcohol-fed rats compared to plasma of pair-fed controls. Future studies will investigate further the functionality of the hub proteins affected by alcohol feeding in both lymph and plasma.

Interruption of TRPC6-NFATC1 signaling inhibits NADPH oxidase 4 and VSMCs phenotypic switch in intracranial aneurysm

Intracranial aneurysm (IA) is a frequent cerebrovascular disorder with unclear pathogenesis. The vascular smooth muscle cells (VSMCs) phenotypic switch is essential for IA formation. It has been reported that Ca2+ overload and excessive reactive oxygen species (ROS) are involved in VSMCs phenotypic switch. The transient receptor potential canonical 6 (TRPC6) and NADPH oxidase 4 (NOX4) are the main pathway to participate in Ca2+ overload and ROS production in VSMCs. Ca2+ overload can activate calcineurin (CN), leading to nuclear factor of activated T cell (NFAT) dephosphorylation to regulate the target gene's transcription. We hypothesized that activation of TRPC6-NFATC1 signaling may upregulate NOX4 and involve in VSMCs phenotypic switch contributing to the progression of IA. Our results showed that the expressions of NOX4, p22phox, p47phox, TRPC6, CN and NFATC1 were significantly increased, and VSMCs underwent a significant phenotypic switch in IA tissue and cellular specimens. The VIVIT (NFATC1 inhibitor) and BI-749327 (TRPC6 inhibitor) treatment reduced the expressions of NOX4, p22phox and p47phox and the production of ROS, and significantly improved VSMCs phenotypic switch in IA rats and cells. Consistent results were obtained from IA Trpc6 knockout (Trpc6-/-) mice. Furthermore, the results also revealed that NFATC1 could regulate NOX4 transcription by binding to its promoter. Our findings reveal that interrupting the TRPC6-NFATC1 signaling inhibits NOX4 and improves VSMCs phenotypic switch in IA, and regulating Ca2+ homeostasis may be an important therapeutic strategy for IA.

A combination of novel NSC small molecule inhibitor along with doxorubicin inhibits proliferation of triple-negative breast cancer through metabolic reprogramming

Treatment of patients with triple-negative breast cancer (TNBC) has been challenging due to the absence of well-defined molecular targets and the highly invasive and proliferative nature of TNBC cells. Current treatments against TNBC have shown little promise due to high recurrence rate in patients. Consequently, there is a pressing need for novel and efficacious therapies against TNBC. Here, we report the discovery of a novel small molecule inhibitor (NSC33353) with potent anti-tumor activity against TNBC cells. The anti-proliferative effects of this small molecule inhibitor were determined using 2D and 3D cell proliferation assays. We found that NSC33353 significantly reduces the proliferation of TNBC cells in these assays. Using proteomics, next generation sequencing (NGS), and gene enrichment analysis, we investigated global regulatory pathways affected by this compound in TNBC cells. Proteomics data indicate a significant metabolic reprograming affecting both glycolytic enzymes and energy generation through oxidative phosphorylation. Subsequently, using metabolic (Seahorse) and enzymatic assays, we validated our proteomics and NGS analysis findings. Finally, we showed the inhibitory and anti-tumor effects of this small molecule in vitro and confirmed its inhibitory activity in vivo. Doxorubicin is one of the most effective agents in the treatment of TNBC and resistance to this drug has been a major problem. We show that the combination of NSC33353 and doxorubicin suppresses the growth of TNBC cells synergistically, suggesting that NSC33353 enhances TNBC sensitivity to doxorubicin. In summary, our data indicate that the small molecule inhibitor, NSC33353, exhibits anti-tumor activity in TNBC cells, and works in a synergistic fashion with a well-known chemotherapeutic agent.

Bioinformatics analysis constructs potential ferroptosis-related ceRNA network involved in the formation of intracranial aneurysm

Background

Intracranial aneurysm (IA) causes more than 80% of nontraumatic subarachnoid hemorrhages (SAHs). The mechanism of ferroptosis involved in IA formation remains unclear. The roles played by competitive endogenous RNA (ceRNA) regulation networks in many diseases are becoming clearer. The goal of this study was to understand more fully the ferroptosis-related ceRNA regulation network in IA.

Materials and methods

To identify differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs), and differentially expressed lncRNAs (DELs) across IA and control samples, the GEO datasets GSE122897 and GSE66239 were downloaded and analyzed with the aid of R. Ferroptosis DEGs were discovered by exploring the DEGs of ferroptosis-related genes of the ferroptosis database. Potentially interacting miRNAs and lncRNAs were predicted using miRWalk and StarBase. Enrichment analysis was also performed. We utilized the STRING database and Cytoscape software to identify protein-protein interactions and networks. DAB-enhanced Prussian blue staining was used to detect iron in IA tissues.

Results

Iron deposition was evident in IA tissue. In all, 30 ferroptosis DEGs, 5 key DEMs, and 17 key DELs were screened out for constructing a triple regulatory network. According to expression regulation of DELs, DEMs, and DEGs, a hub triple regulatory network was built. As the functions of lncRNAs are determined by their cellular location, PVT1-hsa-miR-4644-SLC39A14 ceRNA and DUXAP8-hsa-miR-378e/378f-SLC2A3 ceRNA networks were constructed.

Conclusion

CeRNA (PVT1-hsa-miR-4644-SLC39A14 and DUXAP8-hsa-miR-378e/378f-SLC2A3) overexpression networks associated with ferroptosis in IA were established.

Analysis of Clinical Effects of Comprehensive Nursing Based on Enhanced Recovery after Surgery in Patients with Embolization for Intracranial Aneurysms

Objective. This research sets out to elucidate the clinical effect of comprehensive nursing based on the concept of enhanced recovery after surgery (ERAS) in patients with embolization for intracranial aneurysms (IAs). Methods. This study enrolled 119 patients with embolization for IAs in the Zhongnan Hospital of Wuhan University from January 2020 to January 2021 and divided them into two groups according to the perioperative care they received: a control group ( $n=39$ ) treated with routine perioperative nursing and an observation group ( $n=80$ ) treated with ERAS-based comprehensive nursing. Surgical indicators, neurological function (National Institute of Health Stroke Scale (NIHSS) score; Scandinavian Stroke Scale (SSS) score), anxiety and depression (Self-Rating Anxiety Scale (SAS) score; Self-Rating Depression Scale (SDS) score), incidence of adverse events, and patient satisfaction were compared. Results. The observation group had better surgical indicators and lower scores of NIHSS, SSS, SAS, and SDS than the control group, accompanied by a lower incidence of adverse events and higher patient satisfaction. Conclusions. ERAS-based comprehensive nursing can better promote patients’ neurological recovery after embolization for IAs, relieve unhealthy emotions (depression, anxiety, etc.), and reduce the occurrence of adverse reactions, facilitating patient discharge.

Repurposing Dimethyl Fumarate for Cardiovascular Diseases: Pharmacological Effects, Molecular Mechanisms, and Therapeutic Promise

Dimethyl fumarate (DMF) is a small molecule that has been shown to assert potent in vivo immunoregulatory and anti-inflammatory therapeutic actions. The drug has been approved and is currently in use for treating multiple sclerosis and psoriasis in the USA and Europe. Since inflammatory reactions have been significantly implicated in the etiology and progression of diverse disease states, the pharmacological actions of DMF are presently being explored and generalized to other diseases where inflammation needs to be suppressed and immunoregulation is desirable, either as a monotherapeutic agent or as an adjuvant. In this review, we focus on DMF, and present an overview of its mechanism of action while briefly discussing its pharmacokinetic profile. We further discuss in detail its pharmacological uses and highlight its potential applications in the treatment of cardiovascular diseases. DMF, with its unique combination of anti-inflammatory and vasculoprotective effects, has the potential to be repurposed as a therapeutic agent in patients with atherosclerotic cardiovascular disease. The clinical studies mentioned in this review with respect to the beneficial effects of DMF in atherosclerosis involve observations in patients with multiple sclerosis and psoriasis in small cohorts and for short durations. The findings of these studies need to be assessed in larger prospective clinical trials, ideally with a double-blind randomized study design, investigating the effects on cardiovascular endpoints as well as morbidity and mortality. The long-term impact of DMF therapy on cardiovascular diseases also needs to be confirmed.

Identification of Potential Core Genes for the Rupture of Intracranial Aneurysms by a Bioinformatics Analysis

Background: Previous studies, using autopsy and angiography, have shown that 3.6–6% of the population have intracranial aneurysms, and the rupture of aneurysm can lead to brain dysfunction or even death in patients.

Methods: To explore potential preventional target genes for the ruptured of aneurysm, we analyze three gene expression datasets (GSE13353, GSE15629 and GSE54083) derived from the GEO database. We confirm DEGs associated with the unrupture of aneurysms by R package. DAVID version provides functional classification and annotation analyses of associated genes, including GO and KEGG pathway. PPI of these DEGs is analyzed based on the string database and visualized by Cytoscape software. DEGs are verified by qRT-PCR using samples isolated from the patients.

Results: 249 overlapping DEGs, including 96 up-regulated genes and 153 down-regulated genes are screened using the Venn diagram webtool. The GO term and KEGG pathways analysis results indicate that these DEGs are mainly enriched in protein phosphorylation, apoptotic process and inflammatory response in the BP term and focal adhesion, thyroid hormone signaling pathway, ErbB signaling pathway, cytokine-cytokine receptor interaction and some disease processes in the KEGG pathways. 6 candidates are confirmed by Cytoscape software and qRT-PCR, including APP, JUN, GSK3B, ErbB2, PPBP and THBS1.

Conclusions: Our data and previous studies show that ErbB2 and THBS1 are crucial to prevent aneurysm rupture, while APP, JUN, GSK3B and PPBP performs the opposite role, and further experiments are needed to verify these findings.

Pharmacological inhibition of epidermal growth factor receptor attenuates intracranial aneurysm formation by modulating the phenotype of vascular smooth muscle cells

Aim

To study the effect of pharmacological inhibition of epidermal growth factor receptor (EGFR) on intracranial aneurysm (IA) initiation.

Methods

Human IA samples were analyzed for the expression of p‐EGFR and alpha smooth muscle actin (α‐SMA) by immunofluorescence (IF). Rat models of IA were established to evaluate the ability of the EGFR inhibitor, erlotinib, to attenuate the incidence of IA. We analyzed anterior cerebral artery tissues by pathological and proteomic detection for the expression of p‐EGFR and relevant proteins, and vessel casting was used to evaluate the incidence of aneurysms in each group. Rat vascular smooth muscle cells (VSMCs) and endothelial cells were extracted and used to establish an in vitro co‐culture model in a flow chamber with or without erlotinib treatment. We determined p‐EGFR and relevant protein expression in VSMCs by immunoblotting analysis.

Results

Epidermal growth factor receptor activation was found in human IA vessel walls and rat anterior cerebral artery walls. Treatment with erlotinib markedly attenuated the incidence of IA by inhibiting vascular remodeling and pro‐inflammatory transformation of VSMC in rat IA vessel walls. Activation of EGFR in rat VSMCs and phenotypic modulation of rat VSMCs were correlated with the strength of shear stress in vitro, and treatment with erlotinib reduced phenotypic modulation of rat VSMCs. In vitro experiments also revealed that EGFR activation could be induced by TNF‐α in human brain VSMCs.

Conclusions

These results suggest that EGFR plays a critical role in the initiation of IA and that the EGFR inhibitor erlotinib protects rats from IA initiation by regulating phenotypic modulation of VSMCs.

Chronic binge alcohol and ovariectomy dysregulate omental adipose tissue metaboproteome in simian immunodeficiency virus-infected female macaques

Effective antiretroviral therapy (ART) has significantly reduced mortality of people living with HIV (PLWH), and the prevalence of at-risk alcohol use is higher among PLWH. Increased survival and aging of PLWH is associated with increased prevalence of metabolic comorbidities especially among menopausal women, and adipose tissue metabolic dysregulation may be a significant contributing factor. We examined the differential effects of chronic binge alcohol (CBA) administration and ovariectomy (OVX) on the omental adipose tissue (OmAT) proteome in a subset of simian immunodeficiency virus (SIV)-infected macaques of a longitudinal parent study. Quantitative discovery-based proteomics identified 1,429 differentially expressed proteins. Ingenuity Pathway Analysis (IPA) was used to calculate z-scores, or activation predictions, for functional pathways and diseases. Results revealed that protein changes associated with functional pathways centered around the "OmAT metaboproteome profile." Based on z-scores, CBA did not affect functional pathways of metabolic disease but dysregulated proteins involved in adenosine monophosphate-activated protein kinase (AMPK) signaling and lipid metabolism. OVX-mediated proteome changes were predicted to promote pathways involved in glucose- and lipid-associated metabolic disease. Proteins involved in apoptosis, necrosis, and reactive oxygen species (ROS) pathways were also predicted to be activated by OVX and these were predicted to be inhibited by CBA. These results provide evidence for the role of ovarian hormone loss in mediating OmAT metaboproteome dysregulation in SIV and suggest that CBA modifies OVX-associated changes. In the context of OVX, CBA administration produced larger metabolic and cellular effects, which we speculate may reflect a protective role of estrogen against CBA-mediated adipose tissue injury in female SIV-infected macaques.

Potential therapeutic effects of Nrf2 activators on intracranial hemorrhage

Intracranial hemorrhage (ICH) is a devastating disease which induces high mortality and poor outcomes including severe neurological dysfunctions. ICH pathology is divided into two types: primary brain injury (PBI) and secondary brain injury (SBI). Although there are numerous preclinical studies documenting neuroprotective agents in experimental ICH models, no effective drugs have been developed for clinical use due to complicated ICH pathology. Oxidative and inflammatory stresses play central roles in the onset and progression of brain injury after ICH, especially SBI. Nrf2 is a crucial transcription factor in the anti-oxidative stress defense system. Under normal conditions, Nrf2 is tightly regulated by the Keap1. Under ICH pathological conditions, such as overproduction of reactive oxygen species (ROS), Nrf2 is translocated into the nucleus where it up-regulates the expression of several anti-oxidative phase II enzymes such as heme oxygenase-1 (HO-1). Recently, many reports have suggested the therapeutic potential of Nrf2 activators (including natural or synthesized compounds) for treating neurodegenerative diseases. Moreover, several Nrf2 activators attenuate ischemic stroke-induced brain injury in several animal models. This review summarizes the efficacy of several Nrf2 activators in ICH animal models. In the future, Nrf2 activators might be approved for the treatment of ICH patients.

Dimethyl fumarate improves cognitive deficits in chronic cerebral hypoperfusion rats by alleviating inflammation, oxidative stress, and ferroptosis via NRF2/ARE/NF-κB signal pathway

Cerebrovascular disease and its risk factors cause persistent decrease of cerebral blood flow, chronic cerebral hypoperfusion (CCH) is the major foundation of vascular cognitive impairment (VCI). The hippocampus is extremely vulnerable to cerebral ischemia and hypoxia. Oxidative stress and neuroinflammation injury are important pathophysiological mechanisms of this process, which is closely related to hippocampal neurons damage and loss. Dimethyl fumarate (DMF), an FDA-approved therapeutic for multiple sclerosis (MS), plays a protective role in multiple neurological disorders. Studies have shown that DMF exerts anti-inflammatory and antioxidant effects via the NRF2/ARE/NF-κB signaling pathway. Thus, this study aimed to evaluate the neuroprotective effect of DMF in the CCH rat model. Ferroptosis, a novel defined iron-dependent cell death form, were found to be strongly associated with the pathophysiology of CCH. Emerging evidences have shown that inhibition of ferroptosis by targeting NRF2 exerted neuroprotective effect in neurodegeneration diseases. We also investigated whether DMF can alleviate cognitive deficits through inhibition of ferroptosis by the NRF2 signaling pathway in this study. DMF was intragastric for consecutive five weeks (100 mg/kg/day). Then behavior test and histological, molecular, and biochemical analysis were performed. We found that DMF treatment significantly improved cognitive deficits and partially reversed hippocampus neuronal damage and loss caused by CCH. And DMF treatment decreased hippocampus IL-1β, TNF-α, and IL-6 pro-inflammatory cytokines concentration, and mediated the NF-κB signaling pathway. And DMF also alleviated hippocampus oxidative stress through reducing MDA, and increasing GSH and SOD levels, which are also closely associated with ferroptosis. Besides, DMF treatment reduced the expression of PTGS2, and increased the expression of FTH1 and xCT, and the iron content is also reduced, which were the important features related to ferroptosis. Furthermore, DMF activated the NRF2/ARE signaling pathway and upregulated the expression of HO-1, NQO1 and GPX4. These outcomes indicated that DMF can improve cognitive impairment in rats with CCH, possibly through alleviating neuroinflammation, oxidative stress damage and inhibiting ferroptosis of hippocampal neurons. Overall, our results provide new evidence for the neuroprotective role of DMF.

Endogenous animal models of intracranial aneurysm development: a review

The pathogenesis and natural history of intracranial aneurysm (IA) remains poorly understood. To this end, animal models with induced cerebral vessel lesions mimicking human aneurysms have provided the ability to greatly expand our understanding. In this review, we comprehensively searched the published literature to identify studies that endogenously induced IA formation in animals. Studies that constructed aneurysms (i.e., by surgically creating a sac) were excluded. From the eligible studies, we reported information including the animal species, method for aneurysm induction, aneurysm definitions, evaluation methods, aneurysm characteristics, formation rate, rupture rate, and time course. Between 1960 and 2019, 174 articles reported endogenous animal models of IA. The majority used flow modification, hypertension, and vessel wall weakening (i.e., elastase treatment) to induce IAs, primarily in rats and mice. Most studies utilized subjective or qualitative descriptions to define experimental aneurysms and histology to study them. In general, experimental IAs resembled the pathobiology of the human disease in terms of internal elastic lamina loss, medial layer degradation, and inflammatory cell infiltration. After the early 2000s, many endogenous animal models of IA began to incorporate state-of-the-art technology, such as gene expression profiling and 9.4-T magnetic resonance imaging (MRI) in vivo imaging, to quantitatively analyze the biological mechanisms of IA. Future studies aimed at longitudinally assessing IA pathobiology in models that incorporate aneurysm growth will likely have the largest impact on our understanding of the disease. We believe this will be aided by high-resolution, small animal, survival imaging, in situ live-cell imaging, and next-generation omics technology.

Comparative bioinformatics analysis between proteomes of rabbit aneurysm model and human intracranial aneurysm with label-free quantitative proteomics

Aims

This study aimed to find critical proteins involved in the development of intracranial aneurysm by comparing proteomes of rabbit aneurysm model and human aneurysms.

Methods

Five human intracranial aneurysm samples and 5 superficial temporal artery samples, and 4 rabbit aneurysm samples and 4 control samples were collected for protein mass spectrometry. Four human intracranial aneurysm samples and 4 superficial temporal artery samples, and 6 rabbit aneurysm samples and 6 control samples were used for immunochemistry.

Results

Proteomic analysis revealed 180 significantly differentially expressed proteins in human intracranial aneurysms and 716 significantly differentially expressed proteins in rabbit aneurysms. Among them, 57 proteins were differentially expressed in both species, in which 24 were increased and 33 were decreased in aneurysms compared to the control groups. Proteins were involved in focal adhesion and extracellular matrix‐receptor interaction pathways. We found that COL4A2, MYLK, VCL, and TAGLN may be related to aneurysm development.

Conclusion

Proteomics analysis provided fundamental insights into the pathogenesis of aneurysm. Proteins related to focal adhesion and extracellular matrix‐receptor interaction pathways play an important role in the occurrence and development of intracranial aneurysm.

Acyl-CoA synthetase long chain family member 4 plays detrimental role in early brain injury after subarachnoid hemorrhage in rats by inducing ferroptosis

Aims

Acyl‐CoA synthetase long chain family member 4 (ACSL4) is closely related to tumor genesis and development in certain tissues. However, the function of ACSL4 in early brain injury (EBI) caused by subarachnoid hemorrhage (SAH) is unclear. In this study, we investigated the expression patterns and role of ACSL4 in SAH and post‐SAH EBI using a rat model of SAH.

Methods

The rat model of SAH was induced by autologous blood injection into the prechiasmatic cistern of rats. We also used two specific inhibitors of ferroptosis (Ferrostatin‐1 and Liproxstatin‐1) to investigate the role of ferroptosis in EBI.

Results

We found that ACSL4 levels in brain tissue increased significantly in post‐SAH EBI. Inhibiting the expression of ACSL4 using small interfering RNAs alleviated inflammation, blood‐brain barrier (BBB) impairment, oxidative stress, brain edema, and behavioral and cognitive deficits, and increased the number of surviving neurons, after SAH. Similar effects were obtained by suppressing ferroptosis.

Conclusions

ACSL4 exacerbated SAH‐induced EBI by mediating ferroptosis. These findings may provide a theoretical basis for potential therapy aimed at alleviating post‐SAH EBI.

Therapeutic Potential of Heme Oxygenase-1 in Aneurysmal Diseases

Abdominal aortic aneurysm (AAA) and intracranial aneurysm (IA) are serious arterial diseases in the aorta and brain, respectively. AAA and IA are associated with old age in males and females, respectively, and if rupture occurs, they carry high morbidity and mortality. Aneurysmal subarachnoid hemorrhage (SAH) due to IA rupture has a high rate of complication and fatality. Despite these severe clinical outcomes, preventing or treating these devastating diseases remains an unmet medical need. Inflammation and oxidative stress are shared pathologies of these vascular diseases. Therefore, therapeutic strategies have focused on reducing inflammation and reactive oxygen species levels. Interestingly, in response to cellular stress, the inducible heme oxygenase-1 (HO-1) is highly upregulated and protects against tissue injury. HO-1 degrades the prooxidant heme and generates molecules with antioxidative and anti-inflammatory properties, resulting in decreased oxidative stress and inflammation. Therefore, increasing HO-1 activity is an attractive option for therapy. Several HO-1 inducers have been identified and tested in animal models for preventing or alleviating AAA, IA, and SAH. However, clinical trials have shown conflicting results. Further research and the development of highly selective HO-1 regulators may be needed to prevent the initiation and progression of AAA, IA, or SAH.

Mast Cell Promotes the Development of Intracranial Aneurysm Rupture

BACKGROUND AND PURPOSE

Inflammation has emerged as a key component of the pathophysiology of intracranial aneurysms. Mast cells have been detected in human intracranial aneurysm tissues, and their presence was associated with intramural microhemorrhage and wall degeneration. We hypothesized that mast cells play a critical role in the development of aneurysmal rupture, and that mast cells can be used as a therapeutic target for the prevention of aneurysm rupture.

METHODS

Intracranial aneurysms were induced in adult mice using a combination of induced systemic hypertension and a single injection of elastase into the cerebrospinal fluid. Aneurysm formation and rupture were assessed over 3 weeks. Roles of mast cells were assessed using a mast cell stabilizer (cromolyn), a mast cell activator (C48/80), and mice that are genetically lacking mature mast cells (Kit^W-sh/W-sh mice).

RESULTS

Pharmacological stabilization of mast cells with cromolyn markedly decreased the rupture rate of aneurysms (80% versus 19%, n=10 versus n =16) without affecting the aneurysm formation. The activation of mast cells with C48/80 significantly increased the rupture rate of aneurysms (25% versus 100%, n=4 versus n=5) without affecting the overall rate of aneurysm formation. Furthermore, the genetic deficiency of mast cells significantly prevented aneurysm rupture (80% versus 25%, n=10 versus n=8, wild-type versus Kit^W-sh/W-sh mice).

CONCLUSIONS

These results suggest that mast cells play a key role in promoting aneurysm rupture but not formation. Stabilizers of mast cells may have a potential therapeutic value in preventing intracranial aneurysm rupture in patients.

Intermittent Hypoxia Promotes Functional Neuroprotection from Retinal Ischemia in Untreated First-Generation Offspring: Proteomic Mechanistic Insights

Purpose

Stress can lead to short- or long-term changes in phenotype. Accumulating evidence also supports the transmission of maladaptive phenotypes, induced by adverse stressors, through the germline to manifest in subsequent generations, providing a novel mechanistic basis for the heritability of disease. In the present study in mice, we tested the hypothesis that repeated presentations of a nonharmful conditioning stress, demonstrated previously to protect against retinal ischemia, will also provide ischemic protection in the retinae of their untreated, first-generation (F1) adult offspring.

Methods

Swiss-Webster ND4 outbred mice were mated following a 16-week period of brief, every-other-day conditioning exposures to mild systemic hypoxia (repetitive hypoxic conditioning, RHC). Retinae of their 5-month-old F1 progeny were subjected to unilateral ischemia. Scotopic electroretinography quantified postischemic outcomes. The injury-resilient retinal proteome was revealed by quantitative mass spectrometry, and bioinformatic analyses identified the biochemical pathways and networks in which these differentially expressed proteins operate.

Results

Significant resilience to injury in both sexes was documented in F1 mice derived from RHC-treated parents, relative to matched F1 adult progeny derived from normoxic control parents. Ischemia-induced increases and decreases in the expression of many visual transduction proteins that are integral to photoreceptor function were abrogated by parental RHC, providing a molecular basis for the observed functional protection.

Conclusions

Our proteomic analyses provided mechanistic insights into the molecular manifestation of the inherited, injury-resilient phenotype. To our knowledge, this is the first study in a mammalian model documenting the reprogramming of heritability to promote disease resilience in the next generation.

Nrf2 dysfunction and impaired cellular resilience to oxidative stressors in the aged vasculature: from increased cellular senescence to the pathogenesis of age-related vascular diseases

Aging is associated with increased oxidative stress in vascular endothelial and smooth muscle cells, which contribute to the development of a wide range of diseases affecting the circulatory system in older adults. There is growing evidence that in addition to increased production of reactive oxygen species (ROS), aging critically impairs pathways determining cellular resilience to oxidative stressors. In young organisms, the evolutionarily conserved nuclear factor-erythroid-2-related factor 2 (Nrf2)-mediated antioxidant response pathway maintains cellular reduction-oxidation homeostasis and promotes a youthful cellular phenotype by regulating the transcription of an array of cytoprotective (antioxidant, pro-survival, anti-inflammatory and macromolecular damage repair) genes. A critical mechanism by which increased ROS production and Nrf2 dysfunction promote vascular aging and exacerbate pathogenesis of age-related vascular diseases is induction of cellular senescence, an evolutionarily conserved cellular stress response mechanism. Senescent cells cease dividing and undergo distinctive phenotypic alterations, contributing to impairment of angiogenic processes, chronic sterile inflammation, remodeling of the extracellular matrix, and barrier dysfunction. Herein, we review mechanisms contributing to dysregulation of Nrf2-driven cytoprotective responses in the aged vasculature and discuss the multifaceted role of Nrf2 dysfunction in the genesis of age-related pathologies affecting the circulatory system, including its role in induction of cellular senescence. Therapeutic strategies that restore Nrf2 signaling and improve vascular resilience in aging are explored to reduce cardiovascular mortality and morbidity in older adults.